The cause of global warming
Greenhouse gases are gaseous compounds (such as carbon dioxide, methane, nitrous oxide or hydrofluorocarbons) that absorb infrared radiation (heat) reflected or emitted from the Earth’s surface and trap that heat in the atmosphere, contributing to the greenhouse effect.
While the greenhouse effect is a natural weather phenomenon, industrial emissions from burning fossil fuels over the last century have accelerated the process. As the planet warms, weather patterns and environments are swiftly changing, affecting icecaps, rainfall, sea levels, flooding, drought, wildfires and vegetation. 2020 was one of the hottest years on record.
What different greenhouse gases are there?
Carbon dioxide (CO2) is released into the atmosphere through the burning of fossil fuels (coal, natural gas and oil), solid waste, or biological materials. CO2 emissions constitute the highest percentage of greenhouse gases globally and are the primary driver for climate change. Once emitted, CO2 is rapidly distributed throughout the entire troposphere within one year.
Methane (CH4) naturally occurs when organic matter decays, but is also emitted by the production of coal, natural gas, and oil. Industrial livestock production and municipal solid waste landfills also contribute to CH4 output. Although CH4 has a shorter lifespan in the atmosphere, it has over 28 times the warming power of CO2 (over a 100 years timespan). The atmospheric concentration of methane is currently increasing at the highest rate since the 1980s.
Nitrous oxide (N2O) is the predominant ozone-depleting substance emitted into the atmosphere, 300 times more powerful than CO2. 25 percent of N2O emissions come from the world’s oceans, but agriculture, industrial processes, fuel-combustion, and wastewater treatment all produce N2O emissions. N2O constitutes about seven percent of greenhouse gas emissions. N2O has a half-life of 114 years in the atmosphere.
Ozone is also depleted by hydrofluorocarbons (fluorinated gases) and other synthetic gases emitted from household, commercial, and industrial applications and processes. These gases are emitted at a smaller rate than other greenhouse gases, but have a high global warming potential (GWP), typically trapping 1,000 to 10,000 times as much heat as CO2. Some synthetic gases remain in the atmosphere for only a few years, and some for thousands of years.
How do we reduce or transform greenhouse gases?
CO2 emissions can be reduced by generating electricity from wind and solar rather than by burning fossil fuels. Power-to-X technologies can create green e-fuels out of green hydrogen and renewable energy. However, about 30 percent of global CO2 emissions are created by hard-to-abate industries like cement, iron, steel, or chemicals, and the oil and gas industry emits tens of millions of tonnes of CH4 annually. In these cases, carbon capture and storage (CCS) technology can help. CCS has the potential to remove 90-99 percent of CO2 and 75 percent of CH4 emissions from these industrial processes by capturing emissions and sequestering them underground.
The majority of N2O emissions come from Nitrogen-based fertilizers. Europe was able to reduce N2O emissions by 21 percent between 1990 and 2010 by employing more efficient practices and reducing applications of N2O based fertilizers. N2O is also a byproduct of fuel combustion, so the introduction of pollution control technologies in cars (catalytic converters) and a growing number of electric vehicles can decrease these greenhouse gas emissions. Refrigeration systems that emit fluorinated gases can look for substitutes with lower GWP as well as improve systems to prevent leaks.
Energy research can take years − even decades − to come to fruition. Companies need patient investors who are willing to work with them over the long term.
What new technologies are being explored?
MAN Energy Solutions is focused on tomorrow, investing in technologies to decrease greenhouse gases like power-to-X, and Carbon Captore and Storage (CCS). To reduce the greenhouse gas emissions in the shipping industry, the future belongs to climate-neutral fuels produced from green hydrogen and renewable energy sources. These include synthetic natural gas (methane), green ammonia and methanol as well as green hydrogen for shorter distances.
While such synthetic fuels are the future, LNG engines are a transitional technology that can be used now to reduce emissions. LNG engines can run also on synthetic fuels without further technical adaptions. With its high heating value and low carbon content, LNG can reduce carbon emissions in shipping already today. MAN’s two- or four-stroke dual-fuel engines have incorporated technologies to eliminate methane slip as well as CO2 emissions.